Catching tool for a loading crane



Jan. 14, 1969 J. H. LINDQVIST CATCHING TOOL FOR A LOADING CRANE Shegt Filed Dec. 18. 1967 JONAS HERMAN LINDIIVIST INVENTOR BY NM! 2:.1 awl Jan. 14, 1969 J. H. LINDQVIST CATCHING TOOL FOR A LOADING CRANE Filed Dec. 18. 1967 Sheet 2 of 4 JONAS HERMAN LWMVISL I INVEN TOR J. H. LINDQVIST '3; 421,791

CATCHING TOOL FOR A LOADING CRANE Jan. 14, 1969 Sheet 3 of 4 Filed Dec. 18. 1967 Fig.5

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Jan. 14, 1969 J. H. LINDQVIST CATCHING TOOL FOR A LOADING CRANE Sheet Filed Dec. 18. 1967 .TONAS- HERMAN LINDGVIST INVENTOR BY mmmm t United States Patent 3,421,791 CATCHING TOOL FOR A LOADING CRANE Jonas Herman Lindqvist, Hudiksvall, Sweden, assignor to HIAB-FOCO Aktiebolag, Hudiksvall, Sweden, a corporation of Sweden Filed Dec. 18, 1967, Ser. No. 691,632 Claims priority, application Sweden, Dec. 20, 1966,

17,391/ 66 US. Cl. 29488 4 Claims Int. Cl. B66c 1/44; B66c 3/16 ABSTRACT OF THE DISCLGSURE The present invention has reference to a catching tool for a loading crane to be used on a truck especially for transporting timber, pulp wood and the like. The purpose of the invention is to reduce the construction height of the tool and to reduce the time required for the loading of the truck. The purpose aimed at is acheived by suspending the catching arms of the catching tool in pendulous link arms which at the upper ends are pivoted at an attachment for the suspension of the tool at the lifting arm of the crane. Further, the catching arms are pivoted in a special way for rendering possible a construction giving the advantages mentioned in the aforegoing.

The present invention has reference to a catching tool for timber, pulp wood or the like. It is intended to be used on a loading crane and in particular in such a connection when the construction height and the catching ability as well as a quick working of the tool is of specialimportance.

The main feature of the invention is to be seen therein that the catching arms are suspended in pendulous link arms which at the upper ends are pivoted at an attachment for the suspension of the tool at the lifting arm of the crane or the like and which with the lower ends are pivoted at the catching arms at a position between on the one hand a common freely suspended link between the arms and on the other hand between one end of a hydraulic piston and cylinder unit and the catching arm in question, said piston and cylinder unit being with the other end pivoted to the upper end of the link arm. A low construction height is obtained for the reason that horizontal or slightly inclining piston and cylinder units may be used. Also for the reason that the catching clows from open position to a load enclosing position have an essentially horizontal movement, there is obtained a low construction height. Due to this low construction height also in closed position of the clows the transfer is facilitated of a load comprising e.g. pulp timber e.g. up past side posts and the like on the load carrying beams on a truck or a trailer. The result will be a reduction of several decimetres for each bundle of pulp wood that is loaded and thus also a shorter loading time than at the use of other catching tools of higher construction having e.g. a vertical hydraulic piston and cylinder unit arranged in the central line of the tool. 1

According to a preferred embodiment of the invention the draw rod of each piston and cylinder unit is arranged in a piston tube rod extending between the piston of the cylinder and a head on the outer end of the draw rod in such a way that an annular space is formed about the draw rod, this space by means of a channel being connected to a source of hydraulic pressure and is in communication with an annular space between the piston rod tube and the part of cylinder about the tube, the cylinder end in front of the piston by means of an axial channel in the draw rod being connected to a source of hydraulic pressure.

Patented Jan. 14, 1969 "ice By means of the special arrangement of the link arms and the hydraulic piston and cylinder units of the catching tool there is obtained on the one hand the low construc tion height described in the aforegoing and on the other hand a very good catching force character. This means that the horizontal catching force will have a high value just after the start of the catching movement when the tool has been brought down into e.g. a pile of wood or timber and the catching clows begin to get hold of the uppermost trunks. In case the timber is frost-bound and is e.g. situated under a snow cover with a thickness of several decimetres, a high initial force is of course of great importance for releasing the frost-bound trunks. When the pile of timber has been displaced a little, it will be easier to fill the catching tool. By means of the shape of the catching arms in combination with the link arms showing the characteristics of the invention, there is obtained via the hydraulic piston and cylinder units the good catching force character and the low construction height mentioned in the aforegoing. By means of this device there is obtained a great force with low speed, when the catching clows work themselves into the timber pile whilst at the opening up of the catching tool, when a smaller force is required, a considerably faster movement of the catching clows is obtained.

The invention will now be elucidated with reference to the accompanying drawings. In the drawings:

FIG. 1 shows a side elevation of a vehicle with a loading crane having a catching tool according to the invention suspended in its lifting arm,

FIG. 2 shows on an enlarged scale a side elevation of the catching tool in closed position,

FIG. 3 is a plan view of the tool,

FIG. 4 is a side elevation of the tool in open position,

FIG. 5 shows a force graph for the catching arms, and

FIG.6 shows on a still more enlarged scale a vertical longitudinal section through one of the hydraulic piston and cylinder units.

The two catching arms 2, 3 of the catching tool 1 shown in the drawings comprise two-armed angle levers with the lower end in the form of catching claws 4. The upper ends of said arms are interconnected by means of a freely suspended pivot 6. The catching arms 2, 3 are suspended in link arms 7 which with the upper ends are journalled to an attachment 8 by means of which the catching tool 1 is adapted to be arranged at the free end of the lifting arm 9 of a loading crane 10 on a truck 11. Between the attachment 8 and the lifting arm 9 there is arranged a rotator 12 for the turning of the catching tool about its vertical axis 13. The lower ends of the link arms 7 are journalled to the catching arms 2, 3. The pivot 14 is situated between the common pivot 6 between the catching arms 2 and 3 and a pivot 15 by means of which a hydraulic piston and cylinder unit 16, 17 is journalled with its lower end to its catching arm 2, 3. The piston and cylinder unit 16, 17 is journalled with the upper end at 18 to the upper ends of the link arms 7. The catching claws 4 are shaped in such a way that they at completely closed catching tool overlap each other (see the broken lines in FIG. 2).

As shown in FIG. 3 there are in the catching tool on either side of the vertical central line 13 used two pairs of link arms 7 diversing in direction downwards and an outwards downwards inclining hydraulic piston and cylinder unit 16, 17. Due to this arrangement of the link arms 7 in pairs and inclining in downward and outward directions there is obtained a good stability of the catching arms 2, 3.

As shown in FIGS. 2 and 4 the catching tool is closed, i.e. the catching claws 4 are swung in direction towards each other when a hydraulic pressure is applied in the 3 hydraulic piston and cylinder units 16, 17 such that the pistons 16 are pressed axially out of their cylinders 17 in question or, more correctly, the cylinders 17 are pressed away from the piston 16 in question.

According to the embodiment shown in FIG. 6 there is a piston 19 displaceable in the interior of the cylinder 17, the draw rod 20 of this piston 19 being at its outer end provided with a head 21. The draw rod 20 is provided with an axial bore 22 which at its inner end is in communication with a cylinder chamber 23 in front of the piston 19 and which at the rear end is in communication with a channel 24 in the head 21 for connection to a source of hydraulic power (not shown). The draw rod 20 is enclosed by a piston rod tube 25 which extends between the piston 19 and the head 21 and which has a considerably greater diameter than the draw rod such that an annular channel 26 is formed between the draw rod and the piston rod tube 25. The ring channel 26 is at its outer end in communication with a channel 27 in the head 21, the channel 27 adapted to be connected to a source of hydraulic power (not shown) and at the inner end through a number of apertures 28 with a ring channel 29 between the piston rod tube 25 and the cylinder 17.

When pressure medium, e.g. oil, is pressed in through the channel 22 into the cylinder chamber 23, the cylinder 17 willdue to the fact that the piston 19 with the draw rod 20 and the head 21 according to FIGS. 2 and 4 is retained at the upper part of the link armbe pressed with the pivot 15 downwards according to FIGS. 2, 4, and 6, the catching arms 2, 3 then being swung in counter clockwise direction or in clockwise direction according to FIG. 2 to completely closed position indicated by Dmin in FIG. 2. Due to the large piston surface the force acting on the catching arms 2, 3 will be large. At said relative displacement between the piston 19 and the cylinder 17 pressure medium will be pressed out of the ring chamber 29 through the apertures 28, the ring chamber 26 and the channel 27 back to a collection receiver (not shown). However, when the catching tool is to be opened, the pressure medium is pressed through the channel 27, the ring channel 26 and the apertures 28 into the ring channel 29. Due to the fact that the surface of the ring channel 29 is considerably smaller than the surface of the cylinder chamber 23, the cylinder 17 will be displaced rather quickly upwards according to FIG. 6. At the same time the force by means of which the arms 2, 3, are influenced will be reduced to a corresponding degree. However, this is of less importance for the reason that the force for opening the catching tool is rather small. The opening movement may at a correct dimensioning of the hydraulical piston and cylinder units be made twice as fast as the closing movement.

Due to the special carrying of the ditferent parts of the catching tool, there is obtained an essentially horizontal movement of the catching claws 4 (see FIG. 4) and as is obvious from the force graph in FIG. the catching force will just after the beginning of the closing movement of the catching arms and the whole time until the closing of the tool (FIG. 2) have its greatest value P.

As shown in FIG. 6 the draw rod 20 is by means of screw threads 30 attached axially in the head 21. By means of this arrangement of the draw rod there is not required any internal sealing between the piston 19 against the tube 25 and the draw rod 20. A sealing device 31 has been arranged between the tube 25 and one end piece 32 of the cylinder 17, and O-rings 33 have been arranged between the piston rod 20 and the head 21. By shaping the draw rod 20 as a light steel tube with an internal flow channel 22 by means of the chosen construction for holding the tube 25 with the head 21 and the piston 19 together there is obtained a light cylinder construction. The lower the weight of the whole catching tool 1 can be made, the greater a loading capacity will be obtained.

The invention has been described in the aforegoing for purposes of illustration only and is not intended to be limited by this description or otherwise except as defined in the appended claims and the different parts of the catching tool may be modified in many ways without departure from the inventive idea. This is true in particular for the shaping of the catching arms 2, 3 and the arrangement of the link arms 7. The catching tool may also be shaped as a catching scoop with the same cylinders and the same link system but with the catching arms shaped as scoop halves for loading of sand and the like. The catching tool 1 may be used in connection with other kinds of cranes than the one shown and may also be suspended in another lifting tool than a lifting arm 9.

What I claim is:

1. A catching tool for a loading crane, said tool provided with catching arms or scoop halves, wherein the improvement comprises suspending the catching arms (2, 3) or the like in pendulous link arms (7) which at their upper end are pivoted to an attachment (8) for the suspension at the lifting arm (9) or the like of the crane and which at their lower end are pivoted to the catching arms (2, 3) or the like at a place situated between on the one hand a common freely suspended pivot (6) between the arms and on the other hand a pivot (15) between one end of a hydraulic piston and cylinder unit (16, 17) and the catching arm (2, 3) in question, this piston and cylinder unit being with one end journalled to the link arms (7) near their upper portion and connected at their other end to pivot (15 2. A catching tool as claimed in claim 1, wherein the improvement comprises arranging a draw rod (20) of the hydraulic piston and cylinder unit (16, 17) axially in a piston rod tube (25) which extends between the piston (19) of the cylinder (17 and a head (21) on the outer end of the draw rod in such a way that an annular interstice (26) is formed about the draw rod, this interstice (26) by means of a channel (27) in the head (21) being in communication with a source of hydraulic power and in communication with an annular interstice (29) between the piston rod tube (25) and the part of the cylinder (17 about the tube, the cylinder end (23) in front of the piston (19) of the cylinder through an axial channel (22) in the draw rod being connected to a source of hydraulic power.

3. A catching tool as claimed in claim 1, wherein the improvement comprises arranging the link arms (7 in pairs on either side of the vertical longitudinal axis (13) of the tool in such a way that they diverge downwards.

4. A catching tool as claimed in claim 1, wherein the improvement comprises attaching the pairs of link arms (7 and the cylinders (17 symmetrically in the catching arms (2, 3) in relation to their freely suspended pivot (6) in such a way that there is obtained an essentially horizontal movement of the catching arm claws (4) at the closing and opening up of the catching tool, the catching force reaching it highest value (P) just after the beginning of its movement and until the closing of the catching arms (2, 4, and 5).

References Cited UNITED STATES PATENTS 

